Paul Manafort, former campaign manager of President Donald Trump, registered as a foreign agent Tuesday because of work he did in the past for a political party in Ukraine that has ties to Russia, according to a report.

Manafort resigned from the Trump campaign in August 2016 after the news surfaced that he and another Trump campaign official, Rick Gates, had helped the Ukrainian Party of Regions funnel money into Mercury and the Podesta Group, which are Washington-based lobbying firms through a nonprofit organization called the European Centre for a Modern Ukraine.

In the forms that Manafort filed with the Department of Justice (DOJ) Tuesday, he revealed that he made $17.1 million over a span of two years that he had been associated with the Ukrainian party, run by former Ukrainian President Viktor Yanukovych who fled to Russia after he was ousted as a leader in 2014, Washington Examiner reported.

Read: Paul Manafort’s Bank Records Sought By Justice Department In Russia Probe

In the document that Manafort filed with the DOJ, he stated that during the period that he worked for the Ukrainian party, he provided: "strategic counsel and advice to members of the Party of Regions regarding their interaction with U.S. government officials and other western influential persons to advance the goal of greater political and economic integration between Ukraine and the West," Politico reported. 

Even though such disclosures are required to be made by the Foreign Agents Registration Act (FARA) for any citizen of the United States advocating on behalf of a foreign government or political party, Manafort chose to wait till this week to register with the DOJ. This is in spite of the fact that Trump’s former campaign manager is being investigated for possible collusion with Russian officials by special counsel Robert Mueller.

Jason Maloni, a Manafort spokesman, refused to go into details about what took Manafort so long to register as a foreign agent. Instead, he simply told Politico that Manafort had “started this process [registering as a foreign agent] in concert with FARA’s unit in September and well before any formal investigation of election interference began.”

Read: Dennis Whitfield, Senior Advisor Of FBI-Raided Strategic Campaign Group, Linked To Paul Manafort, Roger Stone

“Paul’s primary focus was always directed at domestic Ukrainian political campaign work, and that is reflected in today’s filing,” he added.

Manafort is the second former member of the Trump campaign to register as a foreign agent after former National Security Advisor Michael Flynn registered as a foreign lobbyist in March for work he did on behalf of the Turkish government. 

Mike Flynn Former National Security Advisor Michael Flynn sits before President Donald Trump and Japanese Prime Minister Shinzo Abe hold a joint press conference at the White House in Washington, D.C., Feb. 10, 2017. Photo: Getty Images/Mario Tama

However, Maloni made it clear that the two cases should not be compared as Flynn’s actions were not the same as Manafort’s.

“Paul’s work ended well before he joined Candidate Trump’s campaign,” Maloni said. “Unlike Flynn, Paul was not simultaneously working as a foreign agent while he was working for Trump.”

Some of the names that Manafort mentioned in the document, suggesting that he was in contact with them regarding his Ukrainian political campaign work, are Rep. Dana Rohrabacher (R-California), former U.S. diplomat and policy expert Paula Dobriansky and vice president of National Endowment for Democracy Nadia Diuk.